It is well known to replace damaged human heart valves with prostheses devices having movable vanes, flaps or balls which allow blood flow in one direction and prevent blood flow back in the opposite direction. Many different designs based on a variety of concepts have been suggested with a large number the subject of United States patents.
The present invention is directed to an artifical heart valve of the type having a vane in the form of a disc which is pivotally mounted within a base in the form of a ring. The heart valve described and illustrated in U.S. Pat. No. 3,476,143 to Kaster is typical of this type of unit. In such heart valves, the vane is hemodynamically opened (when it is in the aortic or pulmonic orifice, respectively) by systolic contraction of the ventricles of the heart which forces blood against the vane. At the onset of diastole, the pressure in the ventricles drops towards zero and the pressure of the blood in the aorta or pulmonary artery acts in a reverse direction on the vane causing it to close. In the mitral or tricuspid position, the valve is opened during diastole when blood pressure in the atrium is higher than in the ventricle, and is closed during ventricular systole when the pressure in the ventricle exceeds that of the atrium.
Besides pivotal movement, the vane is arranged to undergo rotational and translatory movements. By permitting the vane to rotate about its axis and to float within its base, the likelihood of blood clot formations at the pivot points of the vane is reduced, thereby reducing the likelihood of thrombosis. The importance of this feature is set out in U.S. Pat. No. 4,057,857 to Fettel. The present invention is directed to an artificial heart valve which provides increased float of the vane to reduce even more the likelihood of thrombosis, regardless of the position it is located in the heart, namely the mitral, tricuspid, pulmonic or aortic positions.
For a discussion of the Omniscience Cardiac Valve Prosthesis, which is an improvement over the Lillehei-Kaster valve (which has been in general use since 1971), reference is made to Omniscience Cardiac Valve Prosthesis Clinical Review 1, by R. A. Dewall, and A. A. Mikhail. For an evaluation in-vitro of the valve, see Scientific Evaluation of In-Vitro Performance of the Omniscience Cardiac Valve by Huffstutler, a paper presented at the 34th Annual Conference on Engineering in Medicine and Biology (Houston, September 1981). Another report about the valve is found in Analytical Design Fundamentals of the Omniscience Cardiac-Valve Prosthesis by Huffstutler, presented at the ASTM Symposium in Phoenix, May 1981. A state of the art review is found in Loss of Pressure for Valve-Opening Surface of the Bjork-Shiley/cc-Omniscience-, by J. Kohler, G. Ehrentraut, B. Stormer, RWTH Aachen in April, 1981 at the Annual Conference of the German Association for Heart and Circulatory Research in Bad Nauheim.